This invention relates to an air tempering apparatus for use in an automotive vehicle having a duct through which air is directed into a passenger compartment.
Air tempering apparatus have sometimes utilized an air cooling heat exchanger for chilling air directed into a passenger compartment, and an air heating heat exchanger for reheating the chilled air to determine a final temperature of tempered air discharged into the passenger compartment. The air cooling heat exchanger includes an evaporator having a variable refrigerating capacity. The evaporator is associated with a variable displacement compressor. The compressor is controlled based upon ambient temperature and compartment temperature in such a manner as to have an increased displacement to increase the refrigerating capacity of the evaporator when the ambient temperature and/or the compartment temperature increases. With such conventional air tempering apparatus, however, the refrigerating capacity will increases to decrease the compartment humidity to a great extent having an adverse effect on the passenger's health, for example, during the daytime in summer. It may be considered to avoid such an adverse effect merely by decreasing the refrigerating capacity when the compartment temperature is less than a predetermined value. However, this results in an undesirable increase in the target tempered air temperature.